Performance improvements in storage and processors, along with the move to distributed architectures such as client/server systems, have spawned increasingly data-intensive and high-speed networking applications, such as multimedia and scientific visualisation. Such applications have placed growing demands of the performance on the interconnects between host computers and input/output devices in terms of their reliability, speed and distance.
Fibre Channel (FC) is a general name for an integrated set of standards being developed by ANSI (American National Standards Institute) whose purpose is to act as a universal high-speed interface for computers and mass storage. It is designed to combine the best features of channels and networks, namely the simplicity and speed of channel communications and the flexibility and interconnectivity of protocol-based network communications. FC is a data transfer protocol that provides a highly reliable, gigabit interconnect technology that allows concurrent communications among workstations, mainframes, servers, data storage systems and other peripherals using Small Computer Systems Interface (SCSI) and Internet Protocol (IP) protocols. FC supports multiple topologies, including a Fibre Channel Arbitrated Loop (FC-AL), which can scale to a total system bandwidth on the order of a terabit per second. However, system performance limitations may be introduced as a result of inefficient system configuration, e.g., where a legacy device on a network bus determines the overall bus speed. In such situations, it is clearly of benefit for a network analyst to be able to monitor the performance of the network and optimise its configuration and/or diagnose faults.
When a problem occurs on a Fibre Channel Arbitrated Loop (FC-AL) it can be extremely difficult to determine the nature of the problem and identify which device on the loop is causing the problem. This is the case because from a logical point of view, an arbitrated loop is a single, continuous path composed of links and nodes, wherein each node has at least one port which can act as a transmitter, receiver or both. Hence it can be difficult to identify the specific node involved in a device failure since there may be no obvious indication of the location of the failure point in the loop.
Conventional analysers of a Fibre Channel Arbitrated Loop (FC-AL) performance are large and expensive stand-alone devices, which are usually connected to a FC-AL, only when it is suspected that a problem exists thereon. Such stand-alone FC-AL analysers provide very detailed analyses of bus traffic, in addition to a wide range of user-selectable capture modes and triggering options.